On Filaments and Nozzle Unclogging

On Filaments and Nozzle Unclogging

There are a number of different material types (filaments) that you can use for building models. So far I have experimented with 3 types and would like to share that with you.

PLA

PLA is Polylactic Acid. It is made from renewable resources, like corn starch or sugar, and is the standard "starter filament" for novice 3D printing. It is also about 10% cheaper than other filaments. It has a lower melting temperature that the other filaments discussed here. It is also less "sticky" when molten. This means a couple of things, it has worse adhesion (both to itself and to printer table) but this lower adhesion appears to mean that it is better at high resolution. This means you can print more precise little things (like, for instance, Hulks Face) than you can with ABS or Flexible Tough. (I need to print a Hulk Face with the ABS and FlexT for comparison).

My main problem with PLA is that it seems to get clogged in the nozzle after a few hours and then the print goes low quality (or just quits). I have not had this happen with other filaments. I have developed a method for cleaning the nozzle and getting the PLA clog out, but it is a little distressing to have to do this after every print. 

PLA is right about in between the ABS and FlexT for flexibility.

Update: I have replace my nozzle with a new one and started a new reel of PLA. I am having excellent luck. I have printed a number of things and I am getting good solid strong results with much less warping (than ABS) and much less of that stringy results.

The PLA was tough enough to push the rollers in with a VICE.

ABS

Acrylonitrile Butadiene Styrene. Wow, that sounds a lot more plastic-y than something with Lactic Acid. This is the same plastic that Legos are made from. In fact, you could probably print a Lego with your 3D printer. I think this stuff is more stiff and sticky than PLA, but I have read articles on the net that say the opposite. Very confusing. On my printer, this stuff is really easy to use. It never gets clogged in the nozzle and it adheres very well to the print bed. It also comes off of the raft very cleanly. So easy to work with.

See the little threads between the towers?

The problem I have with it is that it makes for long after strings. These are tiny little spider web strings of filament that flow between parts of the model when the head is moving through open air without extruding. Imagine you are doing a print of two towers standing next to each other. You build from the floor up. So sometimes the head will be adding plastic to one tower, then it will move through the air to the other tower and add plastic there; always staying at the same height for each tower and then moving up a notch and repeating. When the head moves from one tower to the other it will often carry a spider string of filament along with it. These things build up and you get a little spider web between the towers and a lot of rough stuff at the edges of the towers. This isn't a huge deal, just makes the finished model less smooth.

Tough Flexible

This may be a M3D only ink. They have this to say about it:

Tough 3D Ink® is a proprietary blend made exclusively by M3D and it is a non-toxic biodegradable thermoplastic. Tough offers unprecedented utility for 3D printing due to its strength and controlled amount of flexibility. When compared to traditional filaments which have a fraction of the bond strength and are typically brittle when printed, Tough 3D Ink is bonded at full strength, allowing you to print longer-lasting objects. Tough is great for medium and large models that need to hold up in the real world or need lots of give.

What I have to say is: it is very flexible. Very sticky. Makes very strong flexible models. But if you don't want the model to be flexible, like you want it to hold something up, then this is a problem. Also, it is way too sticky to be able to use supports or rafts. The supports and rafts are very strong and very difficult to remove from the model. That is non-ideal.

Given that, however, it would be a great choice for things like bracelets or pencil holders and just about anything that you want to pick up that doesn't have to be firm.

Flexible

Nozzle Unclogging - the JNP way.

One of the big problems with 3D printing seems to be a clogged nozzle. You nozzle can get clogged for a number of reasons, but the most likely culprits seem to be:

1. A filament spool that isn't feeding properly. If the filament gets held up and doesn't feed strongly, you can get some plastic stuck in the nozzle. PLA seems especially prone to this.
2. Dust or dirt on the filament.
3. Poor quality filament. (once again, PLA seems to be prone to this, though perhaps I just have a bad spool of PLA).
4. Water in the filament. Most filaments are water absorbent, so you are supposed to keep them stored in a baggie with some water absorber stuff. I suspect that as filaments sit around your room, they "go bad" because they absorb moisture.
5. Changing filament types. The lower temperature PLA can't clear the higher temperature filaments out of the nozzle. And the higher temperatures can burn the PLA and leave burnt flakes that won't get soft and exit the nozzle.

Note that all of these things seems to be exacerbated by PLA (or at least the 2 PLA reels that I have tried to work with).

If you search around the internets, you will find a number of methods to try and unclog your nozzle. You can try manually pushing filament through (sort of over pressurizing the nozzle). You can try putting a piece of wire (perhaps guitar string wire) up the nozzle and swirling it around (may have to try this a number of times says the directions). 

The most reliable method is something called a cold pull (or an atomic pull). You put some filament into your nozzle at normal melting temperature and get it to come out the nozzle as much as it will. Then you let the temperature cool until the filament is just a little more solid. Then you pull on the filament (from the spool end) and just pull that clog right out of the hot end. Yank it out. 

The problem with this is that my fool proof M3D Mini (which I just was notified will no longer be sold so order one soon !!!)  doesn't give me control of the temperature (directly). Also, there isn't a way to put filament into the nozzle without also feeding it through the extruder gears, which means that you can't pull it out hard without breaking something. Drat.

However, I have found a different method that seems to work well for me. I call it the "Tough Transparent Love" method.

Tough Transparent Love Method

On a Micro, it works like this:

 First do the process for removing your existing filament (probably PLA). On the  micro, this means hitting the "remove filament" button and waiting. Perhaps pulling the old stuff out when instructed.
Once that is done, do the process for inserting a new filament, but insert a piece of Tough 3D ink. I recommend using the Durable Transparent color as this makes it easy to see the remaining color PLA or ABS that you are clearing from the nozzle. As the filament loads, it will first push out the old stuff, then you get some clear, then.... you get some more color. I think this additional color is the clog coming out. I think this happens because, though the Tough ink has a similar operating temperature as PLA, it is much stickier. So it sticks to the clog and pulls it out with the extrude. When the Mini software asks of the new filament has been extruded, I say NO a couple of times, or until the ink coming out is completely clear, with no residual previous ink color. 

Now, do an unload of the Tough ink and load with whatever it is you intend to print with. The has been working well for me. Of course, I have just about switched to using only the ABS-R from M3D and that doesn't appear to have any nozzle clogging problems.

Using Different Nozzles.

I have 2 nozzles right now. I am going to assign one to only be PLA and see what happens with that. The other one will be for Tough or ABS. Lets go see how hard it is to switch out the nozzle. Second Nozzle for PLA is working great. Makes me doubt the entire ABS use thing. Well except for the heat part.
Note: My second nozzle quit working well for my Blue PLA. I am suspicious now of my blue PLA. Could it be because the code letters for M3D are COW?

On a Heated Chamber.

I took a cardboard box. Turned it upside down. Put it over my printer. Put a little electric space heater in there and turned it on low. Hoping this would help with ABS cohesion and warping.
Instead. it did this to my PLA components (in blue).

HA. PLA melts pretty quick